Valve devices are used to block a passage where fluid flows. Such valve devices include a valve member that is movable toward and away from a valve seat in a valve body. In this type of valve devices, the valve member abuts against the valve seat for valve closing, and the valve member separates from the valve seat for valve opening. A position of the valve member is controlled by a movable member of a driving unit. For example, the valve member is electromagnetically driven.
The valve devices include a normally-open type valve in which a valve is opened when a driving unit does not operate and a normally-close type valve in which a valve is closed when a driving unit does not operate. In the normally-open type, when a driving unit is not operating, a valve member is biased in a valve opening direction by a biasing member to move away from a valve seat. A movable member moves in the valve closing direction against the biasing force of the biasing member to permit the valve member to move toward the valve seat when the driving unit is operating.
In the normally-close type, when a driving unit is not operating, a valve member is biased by a biasing member in the valve closing direction to abut against a valve seat. When the driving unit is operating, a movable member moves in the valve opening direction against the biasing force of the biasing member to permit the valve member to move oppositely to the valve seat.
The above valve device is disclosed in Patent Documents 1 to 7, for example. A fuel suction valve of a high pressure pump disclosed in Patent Documents 1 and 2 is a normally-open type valve provided with an electromagnetic driving unit. When a valve member moves apart from a valve seat, a fuel flows through a passage between a radially outer wall surface of the valve member and an inner wall surface of a valve body. The valve member shown in Patent Document 1 receives a fuel flow from a pressurization chamber at a time of metering stroke of the high pressure pump. At this time, a dynamic pressure on the valve member becomes large especially at high speed operation of the high pressure pump. Meanwhile, in a fuel suction valve shown in Patent Documents 2, a stopper that inhibits movement of a valve member in the valve opening direction is provided at a pressurization chamber to prevent fuel flowing from the pressurization chamber from directly hitting the valve member.
A fuel suction valve of the high pressure pump disclosed in Patent Document 3 is a normally-close type valve provided with an electromagnetic driving unit. The fuel suction valve includes a movable member at its axial center. An elastic plate member is shifted by the movable member to ensure a passage from a pressurization chamber to a fuel gallery. Gas valves disclosed in Patent Documents 4 to 6 are a normally-open type valve and a normally-close type valve provided with an electromagnetic driving unit.
Flow control valves disclosed in Patent Document 7 are a normally-close type valve device and a normally-open type valve device provided with a driving unit formed of a piezo actuator. In the valve devices shown in Patent Documents 3 to 7, fluid flows through the multiple first passages of the valve member at the time of valve opening. At this time, a dynamic pressure in a valve opening direction generated by a flow of fluid is applied to portions other than the first passages of the valve member.
[Patent documents 1] JP-2004-218633A
[Patent documents 2] JP-2010-156264A
[Patent Document 3] US-2010-0242922A1
[Patent Document 4] US-2007-0057096A1
[Patent Document 5] U.S. Pat. No. 7,124,998B2
[Patent documents 6] JP-11-311150A
[Patent documents 7] JP-2010-230159A
The valve member show in Patent Document 1 is not structured to avoid the dynamic pressure generated by a flow of fuel from the pressurization chamber. Therefore, to prevent a self-closing in which the valve member is closed by the dynamic pressure, a large biasing force of the biasing member may be required to bias the valve member in the valve opening direction. Accordingly, an attraction force of an electromagnet of the driving unit increases to move the movable member against the biasing force of the biasing member. This causes a disadvantage that the driving unit has a large size.
If a lift amount of the valve member from the valve seat is too small, a required fluid passage area is not securable. Therefore, it may be difficult to make the lift amount small. The electromagnet of the driving unit may need to generate an attraction force to attract the movable member, which is more than the lift amount. This also causes enlargement of the driving unit.
In the fuel suction valve shown in Patent Document 2, a wringing generated between the valve member and the stopper may deteriorate a valve closing responsiveness. The wringing force on the valve member can be reduced by forming a communicating hole in a stopper. However, when the communicating hole is too large, fuel flows into the stopper through the communicating hole. This fuel flow is applied to the valve member in the valve closing direction. Therefore, it is difficult to inhibit self-closing of the valve member sufficiently. Since a tuning of the inner diameter of the communicating hole depends on a kinetic viscosity of fuel and a flow velocity of fuel, the tuning may need to be changed in response to a cam specification and a highest pump rotation speed required by a user.
In the valve devices of Patent Documents 3 to 7, the multiple first passages are formed to the valve member to make the passage area large. As a result, the lift amount of the valve member from the valve seat can be made small. However, the driving unit is enlarged to prevent self-closing of the valve member.